1. Field of the Invention
The present invention relates to inflatable airbag systems. More specifically, this invention relates to a system for retaining an inflatable cushion in a folded condition.
2. Description of Related Art
Inflatable airbags are well accepted for use in motor vehicles and have been credited with preventing numerous deaths and injuries. Some statistics estimate that frontal airbags reduce the fatalities in head-on collisions by 25% among drivers using seat belts and by more than 30% among unbelted drivers. Statistics further suggest that with a combination of a seat belt and an airbag, serious chest injuries in frontal collisions can be reduced by 65% and serious head injuries by up to 75%. Airbag use presents clear benefits and vehicle owners are frequently willing to pay the added expense for airbags. In addition, the inclusion of inflatable safety restraint devices, or airbags, is now a legal requirement for many new vehicles.
Airbag systems typically include three principal components: an electronic control unit (ECU), an inflator, and an inflatable cushion. The ECU monitors the acceleration and deceleration of the vehicle and determines when accident conditions exist. The ECU is in communication with the inflator and transmits a signal to the inflator when the ECU determines that the vehicle has been involved in an accident.
In response to receipt of the signal, the inflator generates inflation gas. The inflator can be designed to produce inflation gas using various methods. For instance, the inflator may use pyrotechnic techniques or simply release compressed gas. In addition, the inflator may use a combination of both pyrotechnics and compressed gas to produce pressurized inflation gas. The inflator is in fluid communication with the inflatable cushion.
The inflatable cushion receives the gas generated by the inflator and rapidly expands as the gas fills the cushion. The inflatable cushion is made from a flexible material, such as fabric. When expanded, the cushion receives the energy of an occupant impact and dissipates the energy such that injuries are minimized or avoided.
The positioning of the inflated cushion during a crash is critical to proper protection of an occupant. The inflated cushion should be positioned to shield the occupant from impacting hard surfaces within the vehicle, such as the steering wheel, windshield, or dashboard.
The most common type of airbag system stores the cushion and inflator in a compartment in the steering wheel. This type of airbag system is frequently referred to as a driver's side airbag system. When the vehicle is involved in an accident, the cushion receives the gas generated by the inflator, expands, and is propelled out of the compartment in the steering wheel. The cushion is fully inflated in a fraction of a second. The inflated cushion prevents the driver from striking the steering wheel and dissipates the kinetic energy of the occupant to minimize injury to the occupant. Similar airbag systems are frequently installed in the passenger side of the dashboard.
More recently, inflatable curtains have been used to protect vehicle occupants. Prior to deployment, inflatable curtains are generally stored in a compartment located above the side doors of the vehicle. When inflation gas is injected into the curtain, the curtain deploys in a downward direction to prevent the occupant from striking the side windows or doors of the vehicle during an accident.
Prior to installation in a vehicle, inflatable curtains must be tightly folded and secured within a retaining system. Conventional retaining systems may include a retaining sock. In one conventional embodiment, the folded cushion is pulled through a retaining sock having two openings. Thereafter, tabs, which are used to secure the cushion to a vehicle, are pulled through holes in the sock. Unfortunately, the cushion frequently becomes twisted while it is being pulled into the sock. As a result, the assembly line worker must often remove the sock and begin the insertion process again. Even if the sock does not become twisted, the sock itself makes it difficult for the assembly line worker to locate the tabs and pull the tabs through the openings in the sock. This process is time consuming and expensive.
In another conventional embodiment, the sock has an open side that is closed following insertion of the inflatable curtain into the sock. Various mechanical fasteners, such as Velcro, have been used to close the open side of the sock. Unfortunately, these mechanical fasteners are expensive and significantly increase the overall cost of the cushion module. Furthermore, the sock itself requires a significant amount of material, which increases the cost of the module. In addition, significant time is required to attach the mechanical fasteners into the sock.
Accordingly, there is a need in the art for a novel cushion retention system that addresses one or more of the above-listed problems. Such a system is disclosed herein.